<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title></title>
    <style>
    .father {
      width: 300px;
      height: 300px;
      background-color: red;
      margin: 100px auto 0px;
      position: relative;
    }
    .son {
      width: 100px;
      height: 100px;
      background-color: pink;
      position: absolute;
      top: 50%;
      left: 50%;
      margin-top: -50px;
      margin-left: -50px;
    }
    </style>
    <link href="css/style.css" rel="stylesheet">
  </head>
  <body>

    <div class="father">
      <div class="son"></div>
    </div>
    <hr>
  
  </body>
</html>
